NSNumber already preserves whether a value was originally boolean.

Use that instead of rolling it up in _SwiftTypePreservingNSNumber so that we
get the right behavior when we go to write plists.

https://bugs.swift.org/browse/SR-2381

Author: jrose-apple

stdlib/public/SDK/Foundation/Foundation.swift

@@ -158,11 +158,6 @@ internal func _swift_Foundation_TypePreservingNSNumberWithCGFloat(
   _ value: CGFloat
 ) -> NSNumber
 
-@_silgen_name("_swift_Foundation_TypePreservingNSNumberWithBool")
-internal func _swift_Foundation_TypePreservingNSNumberWithBool(
-  _ value: Bool
-) -> NSNumber
-
 @_silgen_name("_swift_Foundation_TypePreservingNSNumberGetKind")
 internal func _swift_Foundation_TypePreservingNSNumberGetKind(
   _ value: NSNumber
@@ -204,11 +199,6 @@ internal func _swift_Foundation_TypePreservingNSNumberGetAsCGFloat(
   _ value: NSNumber
 ) -> CGFloat
 
-@_silgen_name("_swift_Foundation_TypePreservingNSNumberGetAsBool")
-internal func _swift_Foundation_TypePreservingNSNumberGetAsBool(
-  _ value: NSNumber
-) -> Bool
-
 // Conversions between NSNumber and various numeric types. The
 // conversion to NSNumber is automatic (auto-boxing), while conversion
 // back to a specific numeric type requires a cast.
@@ -348,7 +338,7 @@ extension Bool: _ObjectiveCBridgeable {
 
   @_semantics("convertToObjectiveC")
   public func _bridgeToObjectiveC() -> NSNumber {
-    return _swift_Foundation_TypePreservingNSNumberWithBool(self)
+    return NSNumber(value: self)
   }
 
   public static func _forceBridgeFromObjectiveC(
@@ -456,7 +446,7 @@ extension NSNumber : _HasCustomAnyHashableRepresentation {
     case .CoreGraphicsCGFloat:
       return AnyHashable(_swift_Foundation_TypePreservingNSNumberGetAsCGFloat(self))
     case .SwiftBool:
-      return AnyHashable(_swift_Foundation_TypePreservingNSNumberGetAsBool(self))
+      return AnyHashable(self.boolValue)
     }
   }
 }

stdlib/public/SDK/Foundation/TypePreservingNSNumber.mm

@@ -76,11 +76,13 @@ - (const char *)objCType {
   case SwiftCGFloat:
     return @encode(CGFloat);
   case SwiftBool:
-    return @encode(bool);
+    // Bool is represented by CFBoolean.
+    break;
   }
   swift::swift_reportError(
       /* flags = */ 0,
       "_SwiftTypePreservingNSNumber.tag is corrupted.\n");
+  abort();
 }
 
 - (void)getValue:(void *)value {
@@ -102,12 +104,13 @@ - (void)getValue:(void *)value {
     memcpy(value, self->storage, sizeof(CGFloat));
     return;
   case SwiftBool:
-    memcpy(value, self->storage, sizeof(bool));
-    return;
+    // Bool is represented by CFBoolean.
+    break;
   }
   swift::swift_reportError(
       /* flags = */ 0,
       "_SwiftTypePreservingNSNumber.tag is corrupted.\n");
+  abort();
 }
 
 #define DEFINE_ACCESSOR(C_TYPE, METHOD_NAME) \
@@ -139,14 +142,14 @@ - (C_TYPE)METHOD_NAME { \
       return result; \
     } \
     case SwiftBool: { \
-      bool result; \
-      memcpy(&result, self->storage, sizeof(result)); \
-      return result; \
+      /* Bool is represented by CFBoolean. */ \
+      break; \
     } \
     } \
     swift::swift_reportError( \
         /* flags = */ 0, \
         "_SwiftTypePreservingNSNumber.tag is corrupted.\n"); \
+    abort(); \
   }
 
 DEFINE_ACCESSOR(char, charValue)
@@ -178,16 +181,17 @@ - (Class)classForCoder {
 DEFINE_INIT(float, Float)
 DEFINE_INIT(double, Double)
 DEFINE_INIT(CGFloat, CGFloat)
-DEFINE_INIT(bool, Bool)
 
 #undef DEFINE_INIT
 
 SWIFT_CC(swift) extern "C" uint32_t
 _swift_Foundation_TypePreservingNSNumberGetKind(
   NSNumber *NS_RELEASES_ARGUMENT _Nonnull self_) {
   uint32_t result = 0;
-  if ([self_ isKindOfClass: [_SwiftTypePreservingNSNumber class]]) {
+  if ([self_ isKindOfClass:[_SwiftTypePreservingNSNumber class]]) {
     result = ((_SwiftTypePreservingNSNumber *) self_)->tag;
+  } else if (CFGetTypeID(self_) == CFBooleanGetTypeID()) {
+    result = SwiftBool;
   }
   [self_ release];
   return result;
@@ -212,7 +216,6 @@ - (Class)classForCoder {
 DEFINE_GETTER(float, Float)
 DEFINE_GETTER(double, Double)
 DEFINE_GETTER(CGFloat, CGFloat)
-DEFINE_GETTER(bool, Bool)
 
 #undef DEFINE_GETTER
 

validation-test/stdlib/NSNumberBridging.swift.gyb

@@ -128,7 +128,7 @@ NSNumberTests.test("_SwiftTypePreservingNSNumber.init(coder:)")
 NSNumberTests.test("_SwiftTypePreservingNSNumber.copy(zone:)") {
   let n: NSNumber = (42 as Int)._bridgeToObjectiveC()
   expectTrue(isTypePreservingNSNumber(n))
-  let copy = n.copy() as! AnyObject
+  let copy = n.copy() as AnyObject
   expectTrue(n === copy)
 }
 
@@ -197,7 +197,11 @@ NSNumberTests.test("_SwiftTypePreservingNSNumber(${Self}).getValue(_:), objCType
   .forEach(in: ${Self}._interestingValues) {
   input in
   let bridgedNSNumber = input._bridgeToObjectiveC()
+%   if Self == 'Bool':
+  expectTrue(CFGetTypeID(bridgedNSNumber) == CFBooleanGetTypeID())
+%   else:
   expectTrue(isTypePreservingNSNumber(bridgedNSNumber))
+%   end
 
   let expectedObjCType: String
 %   if Self == 'Int':
@@ -229,7 +233,9 @@ NSNumberTests.test("_SwiftTypePreservingNSNumber(${Self}).getValue(_:), objCType
   _UnknownArchError()
 #endif
 %   elif Self == 'Bool':
-  expectedObjCType = "B"
+  // NSNumber always encodes booleans as 'signed char', even on platforms where
+  // ObjCBool is a true Bool. This is a very old compatibility concern.
+  expectedObjCType = "c"
 %   else:
   _UnknownTypeError()
 %   end
@@ -247,13 +253,20 @@ NSNumberTests.test("${Self} bridges to NSNumber (actually _SwiftTypePreservingNS
   input in
   // Bridged NSNumbers preserve the Swift type when put into AnyHashable.
   let bridgedNSNumber = input._bridgeToObjectiveC()
+%   if Self == 'Bool':
+  expectTrue(CFGetTypeID(bridgedNSNumber) == CFBooleanGetTypeID())
+%   else:
   expectTrue(isTypePreservingNSNumber(bridgedNSNumber))
+%   end
   expectNotEmpty(bridgedNSNumber._toCustomAnyHashable())
 
   // Explicitly constructed NSNumbers don't have a special AnyHashable
   // representation.
 %   if Self == 'CGFloat':
   let explicitNSNumber = NSNumber(value: input.native)
+%   elif Self == 'Bool':
+  // Bool actually /is/ type-preserving for NSNumber. Use a dummy value instead.
+  let explicitNSNumber = NSNumber(value: (input ? 1 : 0) as Int8)
 %   else:
   let explicitNSNumber = NSNumber(value: input)
 %   end